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GU N F I D E N T I A L 



SERVICE TEST 



4 



^FLYING WING 

Northrop 






1 - lllippp 






BY AUTHORITY OF 
COMMANDING GENERAL 
AIR MATERIEL COMMAND 
U.S. AIR FORCE 



EIGHT J 35-A-I5 

ALLISON 



WF O-2S JUNE « 500 

20 DEC. 1949 



CONFIDENTIAL 



YB- 49 



SERVICE TEST 



GU N F I D E N T I A L 



J L 



J L 



10 20 30 
i_ I i I i i 



-41.2- 



9 — r 




53.1 











t 




15.2' 



Wing Area 4000 sq ft 

Aspect Ratio 7.4 

M. A. C 315 in. 



Wing Section: 

Root NACA 65. 3-019 

Tip NACA 65. 3-018' 



1239 gal n 
1573 gal 




895 gal 

887 gal 

1573 gal- 

1239 gal 



iWvWM Fuel 



lOil 




FLIGHT ENGINEER 



YB- 49 



20 DEC. 1949 



SERVICE TEST 



GU N F I D E N T I A L 



POWER PLANT 



No. & Model (8) J35-A-15 

Mfr Allison 

Engine Spec. No E-571 

Type & Stages .... Axial Flow (11 ) 

Length 168" 

Diameter 40" 

Weight(dry) 2400 lb 

ENGINE RATINGS 



S. L. Static 



Max: 



Mil: 



Nor: 



LB - RPM 



3750 - 7700 



3750 - 7700 



3270 - 7400 



BIB 


PENSIONS 


Span 


. . . 172. 0' 


Length 


53. 1' 


Height 


15.2' 


Tread 


41 9.< 






The mission of the YB-49 is to further explore and develop the po- 
tentialities of "flying wing type" aircraft. 

The crew consists of a pilot; co-pilot, navigator, bombardier, radio 
operator and engineer. 

The aircraft is a modification of the YB-35 and YB-35A aircraft 
(reciprocating engines) to accommodate eight turbo jet type engines and 
is of "pure" flying wing configuration using elevons - combination ele- 
vators and ailerons - and split type wing tip drag rudders for control. 
Four vertical fins are installed to improve directional stability. 

The electrically operated landing gear is of the tricycle type with 
steerable nose wheel. 

Two auxiliary power units installed in bomb bays 3 and 6 provide 
AC power. Fuel tanks for the APU's are installed in bomb bay 5. 

The crew compartment is pressurized to maintain an equivalent of 
5000 ft altitude up to 28, 000 feet and a constant differential pressure 
above 28, 000 feet. Window defrosting, air conditioning, dust protect- 
ion and sound proofing is ; .-ovided. 



Authorization for conversion from YB-35's to YB-49: June 1945 
First flight: October 1947 
Two service articles completed 

First article acceptance, June 1948; Second article: May 1949 



B 


O M 


B 


s 


No. 


Size 




Type 


2 ... 


. 4000 ... 




G. P. 


5 


.... 2000... 




. G. P. 


10 






. A. P. 


10 


1000 . . . 




. G. P. 


30 


500 . . . 




G. P. 


Max Bomb Load : . . 


. 16, 


000 lb 



V N 



NO PROVISIONS 



WEIGH 


T S 


Loading Lb 


L. F. 


Empty 88, 442(A) 

Basic 90, 173(A) 

Design. . . . 213, 552 
Combat . . *133, 569 
Max. T.Q.H93, 938 
Max Land. . 146, 550 


2. 


(A) Actual 

* For basic mission 
t Limited by space 





JP U E I 

Location No. Tanks Gal. 

Main* 4 5000 

Aux 6 7752 

Bomb bay 2 1790 

*Self-sealing Tot. 14,542 

Spec AN-F-32 

Grade JP-1 

I L 

Capacity (gal) 80 

Spec AN-0-9 

Grade 1010 

ELECTRONICS 

VHF Command AN/ARC- 3 

Liaison AN/ARC-8 

Interphone AN/AIC-2 

Radio Compass AN/ARN-7 

Marker Beacon RC-193 

Localizer RC-103 

Glide Path AN/ARN-5 

IFF SCR- 695 

Range Recvr SCR-274N 



20 DEC. 1949 



CONFIDENTIAL 



YB-49 



SERVICE TEST 



CO NF I D E N T I A L 



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„ ^„ T ^,„.^,. T „ BASIC MAX. BOMB FERRY 



CONDITIONS 



MISSION 



MISSION 



RANGE 



TAKE-OFF WEIGHT 

Fuel at 6. 7 lb/gal 

Military load (Bombs) 

Wing loading 

Stall speed (power off) 

Take-off ground run at SL ®@ 
. Take-off to clear 50 ft ®@ 

Rate-of-climb at SL © 

Time: SL to 20, 000 ft © 

Time: SL to 30, 000 ft © 

Service ceiling (100 fpm) © 
COMBAT RANGE © 

Avg cruising speed 

Cruising altitude (s) 

Total mission time 
COMBAT RADIUS © 
Avg cruising speed 
Cruising altitude (s) 

Total mission time 



(lb) 
(lb) 
(lb) 
(lb/sq ft) 
(kn) 
(ft) 
(ft) 
(fpm) 
(min) 
( min) 
(ft) 
(n. mi) 
(kn) 
(ft) 

(hr ) 
(n. mi ) 
(kn) 
(ft) 

(hr ) 



I 

193, 938 
91, 442 
10, 000 
48. 5 
90 

4850 

5850 

2480 

11.9 

22. 

37, 400 

2828 

365 
33, 800- 
44, 600 

7. 84 
1403 
365 

33, 800- 
46, 200 
7. 87 



II 

193, 539 
85, 438 
16, 000 
48. 4 
90 

4780 
5775 
2470 
11. 8 
21. 8 
37, 500 
2520 
364 
33, 900- 
43, 700 
7. 00 
1322 
365 
33, 900- 
46, 400 
7. 42 



III 

190, 284 
97, 431 
None 
47. 6 
89 
4530 
5470 
2530 
11. 4 
21. 
37, 900 
3105 
365 
34, 500- 
46, 000 
8. 59 



S N 

.0 



COMBAT WEIGHT © (lb) 

Combat altitude (ft) 

Combat speed ©@ (kn) 

Combat climb © (fpm) 

Combat ceiling (500 fpm) © (ft) 

Service ceiling (100 fpm) © (ft) 

Max rate-of-climb at SL © (fpm) 

Max speed at ft ©© (kn/alt) 

LANDING WEIGHT (lb) 

Ground roll at SL © (ft) 

Total from 50 ft (4) (ft) 



133, 569 
35, 000 
403 
1010 
40, 700 
45, 200 
3785 
428/ 

20, 800 
101, 640 
2000 
3875 



129, 870 

41, 600 

403 

480 
41, 300 
45, 700 

3900 
430/ 

20, 000 
100, 645 

1950 

3850 



102,596 
46, 000 

403 

540 
46, 000 
49, 700 

4980 
433/ 

18, 000 
102, 596 

2025 

3920 



olio 

S N 



NOTES on page 6. 

© Take-off power © Radius mission if radius is 

© Max power shown 

S Normal power © Mach number limitation 

Take-off and landing distances are obtainable at sea level using nor- 
mal technique. For airport planning add 25% to distances shown. 
© Detailed descriptions of the RADIUS & RANGE missions are given 



CONDITIONS 

(a) Performance Basis: Calculated data based on manufacturer's flight 
test and wind tunnel test. 

(b) In computing Radius and Range, specific fuel consumptions have been 
increased 5% to allow for variations of fuel flow in service aircraft 

(c) Performance is based on powers shown on page 6. 



YB- 49 



CONFIDENT I A L 



20 DEC. 1949 



GUN F I D E N T I A L 



SERVICE TEST 



o 
o 

o 



H 
U 

<! 
H 
co 





SEA LEVEL 



| CLEAR 50 FTj 



J. 





100 120 140 160 180 200 

GROSS WEIGHT (1000 lb) 




o 
o 
o 



W 
Q 

H 
H 



CO 

H 
O 

Q 

W 
W 
& 

CO 

< 



50 



40 



30 



20 



10 



S.L. 









mm 
















\\ 










MAX POWER 

NORMAL POWER 
















s 




\ 




















\ 




\ 


\ 




















« 

\ 


\ 






















\ 

\ 




> 


> 

\ 




















\ 

\ 




\ 




V 
















> 






^ — 














1 


133, E 


69 LI 


P 












— ^ 


\ 












193, 


938 L 










ft 



















800 1600 2400 3200 4000 

RATE OF CLIMB-FT/MIN 



390 



380 



370 



360 




















| | | | 




193, 938 LB T. O. 
13, 647 GAL. FUEL 








































\ 


























\ 


































































10, 000 LB 










BOMBS 










1 



























































































1300 1400 
NAUTICAL MILES 



20 DEC. 1949 



GO NFIDENTIAL 



YB- 49 



SERVICE TEST 



N f~ I D ti r , ^sl ^1" t i 



NOTES 



FORMULA: RADIUS MISSION I 

Warm-up, take-off and climb on course to 33, 800 ft altitude at max- 
imum power and maximum rate of climb, cruise out at long range speeds 
increasing altitude with decreasing airplane weight, make 6 minute nor- 
mal power bomb-run to target, drop bombs, conduct normal power eva- 
sive action for 6 minutes, start cruise to home base at 41, 100 ft alt- 
itude arriving over home base at 46, 200 ft altitude. Range free allow- 
ances are: 5 minutes normal power fuel consumption for starting eng- 
ines and take-off, plus 6 minutes normal power evasive action, plus 10% 
of initial fuel for landing and endurance reserve. 

FORMULA: RANGE MISSION I 

Same as the outbound leg of the Basic Radius formula continued un- 
til 90% of the initial fuel has been used at 44, 600 ft altitude, leaving 
10% fuel reserve for combat evasive action, landing reserve or other 
consideration for which no distance credit is allowed. 

FORMULA: RADIUS MISSION II 

Same as the Basic Radius formula, initial altitude for start of cruise 
out is 33, 900 ft and final altitude over the home base is 46, 400 ft. Range 
free allowances are the same as for the Basic Radius formula. 



FORMULA: RANGE MISSION III 

Same as the Basic Range formula; initial altitude for start of cruise 
out is 34, 500 ft and final altitude is 46, 000 ft. Range free allowances 
are the same as for the Basic Range formula. 

GENERAL NOTES 

(a) Airplane performance based on engine performance from G. E. 
Bulletin No. DF-81576, dated 26 May 1947. 

(b) Engine ratings shown on page 3 are engine manufacturer's guar- 
anteed ratings. Power values used in performance calculations 
are as follows: 



J35-A-15 

S. L. Static LB - RPM 

T. O. 4000 - 7700 

Max: 4000 - 7700 

Nor: 3500 - 7400 



of 



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IQ 



is. 



°0 A r °l-CQ ij 



YB- 49 



CONFIDENTIAL 



20 DEC. 1949